1,905 research outputs found
Pré-Fabricaçao em edificios habitacionais a custos controlados
Hay una necesidad creciente para la construcción de viviendas, necesidad que se ha incrementado de forma exponencial en las últimas décadas. Esta necesidad es considerable en los países en vías de desarrollo, donde la población tiene una tasa de crecimiento elevada, mucho mayor que en los países desarrollados. Además, la población en el Mundo está desplazándose progresivamente hacia las ciudades. Es en los alrededores de las ciudades de países en desarrollo donde surge una necesidad de construir viviendas de coste controlado, asequibles, que se convierte en algunos casos en crítica. La Comisión de Prefabricación de la fib (International Federation for Structural Concrete, Federation Internationale du Béton, Federación Internacional del Hormigón Estructural) ha sido consciente por muchos años de este problema y tomó la decisión de crear un grupo de trabajo para desarrollar un documento sobre viviendas prefabricadas de coste asequible. Este documento estará dedicado a servir de ayuda sobre las técnicas de la prefabricación para las personas que deseen construir este tipo de viviendas. El presente artículo hace un resumen del trabajo desarrollado por este grupo hasta el momento
Genes involved in carotene synthesis and mating in Blakeslea trispora
Mating of Blakeslea trispora and other molds of the order Mucorales requires the interaction of mycelia of opposite sex, (+) and (-), leading to the development of specialized structures and to an enhanced accumulation of beta-carotene. Industry obtains beta-carotene by co-cultivating appropriate strains of Blakeslea (mated cultures). Gene transcription in single and mated cultures was assayed by cDNA-AFLP, a technique to observe the differential expression of subsets of mRNA fragments. Overexpression in mated cultures is about ten times more frequent than underexpression. We obtained and sequenced fragments of 97 candidate genes that appeared to be overexpressed during mating and confirmed four of them by reverse transcription and real-time PCR. Comparisons with gene sequences from other organisms suggest functions in carotene biosynthesis (4 genes), energy metabolism (8), cell wall synthesis (1), transfer of acetyl groups (1), and regulatory processes (10). Sodium acetate inhibited sexual overexpression in about two-thirds of the candidate genes and acted as a signal with broad effects on the metabolism and the morphology of mated cultures. Our work offers new materials for the study of carotene biosynthesis and its regulation and for the improvement of carotene production with Mucorales
Development of a computer program to simulate the predictions of the replaced elements model of Pavlovian conditioning
Vogel, E.H. Universidad de Talca, Escuela de Psicología, Casilla N° 747, Talca, Chile.
Disponible http://www.psicothema.com/pdf/3392.pdfPese a la aparente simpleza del condicionamiento pavloviano, la investigación acerca de sus mecanismos ha despertado considerable debate, como es el caso de la disputa acerca de si los estímulos que se asocian son codificados en forma >(un estímulo compuesto es equivalente a la suma de sus componentes) o >(un estímulo compuesto es un ejemplar único). Esta controversia es evidente en la abundante investigación sobre las predicciones contrastantes de los modelos elementalistas y configuracionales. Recientemente, han surgido soluciones mixtas, con las ventajas de ambos enfoques, pero difíciles de evaluar dada su complejidad. Este artículo presenta un programa computacional para ejecutar simulaciones de un modelo mixto (replaced elements model o REM). Se incluyen instrucciones y ejemplos para utilizar el simulador con fines investigativos y educacionales
Coupling supergravity to non-supersymmetric matter
By introducing a nonlinearly transforming goldstino field
non-super\-sym\-metric matter can be coupled to supergravity. This implies the
possibility of coupling a standard model with one Higgs to supergravity.Comment: 11 pages, LATEX, references adde
Measurement driven quantum evolution
We study the problem of mapping an unknown mixed quantum state onto a known
pure state without the use of unitary transformations. This is achieved with
the help of sequential measurements of two non-commuting observables only. We
show that the overall success probability is maximized in the case of measuring
two observables whose eigenstates define mutually unbiased bases. We find that
for this optimal case the success probability quickly converges to unity as the
number of measurement processes increases and that it is almost independent of
the initial state. In particular, we show that to guarantee a success
probability close to one the number of consecutive measurements must be larger
than the dimension of the Hilbert space. We connect these results to quantum
copying, quantum deleting and entanglement generation.Comment: 7 pages, 1 figur
Hydrogen sulfide pathway and skeletal muscle: an introductory review.
The presence of the H2 S pathway in skeletal muscle (SKM) has recently been established. SKM expresses the three constitutive H2 S-generating enzymes in animals and humans, and it actively produces H2 S. The main, recognized molecular targets of H2 S, that is, potassium channels and PDEs, have been evaluated in SKM physiology in order to hypothesize a role for H2 S signalling. SKM dysfunctions, including muscular dystrophy and malignant hyperthermia, have also been evaluated as conditions in which the H2 S and transsulfuration pathways have been suggested to be involved. The intrinsic complexity of the molecular mechanisms involved in excitation-contraction (E-C) coupling together with the scarcity of preclinical models of SKM-related disorders have hampered any advances in the knowledge of SKM function. Here, we have addressed the role of the H2 S pathway in E-C coupling and the relative importance of cystathionine β-synthase, cistathionine γ-lyase and 3-mercaptopyruvate sulfurtransferase in SKM diseases
Finite-Temperature Transition into a Power-Law Spin Phase with an Extensive Zero-Point Entropy
We introduce an generalization of the frustrated Ising model on a
triangular lattice. The presence of continuous degrees of freedom stabilizes a
{\em finite-temperature} spin state with {\em power-law} discrete spin
correlations and an extensive zero-point entropy. In this phase, the unquenched
degrees of freedom can be described by a fluctuating surface with logarithmic
height correlations. Finite-size Monte Carlo simulations have been used to
characterize the exponents of the transition and the dynamics of the
low-temperature phase
Voltage dip generator for testing wind turbines connected to electrical networks
This paper describes a new voltage dip generator that allows the shape of the time profile of the voltage generated to be configured. The use of this device as a tool to test the fault ride-through capability of wind turbines connected to the electricity grid can provide some remarkable benefits: First, this system offers the possibility of adapting the main features of the time–voltage profile generated (dip depth, dip duration, the ramp slope during the recovery process after clearing fault, etc.) to the specific requirements set forth by the grid operation codes, in accordance with different network electrical systems standards. Second, another remarkable ability of this system is to provide sinusoidal voltage and current wave forms during the overall testing process without the presence of harmonic components. This is made possible by the absence of electronic converters. Finally, the paper includes results and a discussion on the experimental data obtained with the use of a reduced size laboratory prototype that was constructed to validate the operating features of this new device
Exploring host genetic polymorphisms involved in SARS-CoV infection autcomes: implications for personalized medicine in COVID-19
Objective. To systematically explore genetic polymorphisms associated with the clinical outcomes in SARS-CoV infection in
humans. Methods. This comprehensive literature search comprised available English papers published in PubMed/Medline and
SCOPUS databases following the PRISMA-P guidelines and PICO/AXIS criteria. Results. Twenty-nine polymorphisms located
in 21 genes were identified as associated with SARS-CoV susceptibility/resistance, disease severity, and clinical outcomes
predominantly in Asian populations. Thus, genes implicated in key pathophysiological processes such as the mechanisms
related to the entry of the virus into the cell and the antiviral immune/inflammatory responses were identified. Conclusions.
Although caution must be taken, the results of this systematic review suggest that multiple genetic polymorphisms are
associated with SARS-CoV infection features by affecting virus pathogenesis and host immune response, which could have
important applications for the study and understanding of genetics in SARS-CoV-2/COVID-19 and for personalized
translational clinical practice depending on the population studied and associated environments
- …